Idenix Pharmaceuticals Initiates Proof-of-Concept Study for Protease Inhibitor IDX320 in Hepatitis C Patients

Jun 10, 2010, 08:00 ET from Idenix Pharmaceuticals, Inc.

CAMBRIDGE, Mass., June 10 /PRNewswire-FirstCall/ -- Idenix Pharmaceuticals, Inc. (Nasdaq: IDIX), a biopharmaceutical company engaged in the discovery and development of drugs for the treatment of human viral diseases, today announced that it has initiated a 3-day proof-of-concept study of IDX320, a protease inhibitor for the treatment of hepatitis C virus (HCV) infection, under a Clinical Trial Application (CTA). The study is evaluating IDX320 in treatment-naive hepatitis C genotype 1-infected patients.

"The potent and multi-genotypic activity demonstrated in vitro, as well as the favorable pharmacokinetics observed in healthy volunteers, suggests a promising profile for further development of IDX320," said Jean-Pierre Sommadossi, Ph.D., chief executive officer of Idenix. "The landscape for combination development in HCV is evolving quickly. Assuming favorable results from the IDX320 proof-of-concept study, we plan to discuss with regulatory agencies a direct-acting antiviral combination strategy with IDX320 and IDX184, our HCV nucleotide polymerase inhibitor."

Douglas Mayers, M.D., Idenix's chief medical officer commented, "We are encouraged by the results seen to date with IDX320 and are hopeful that future clinical studies will allow us to continue advancing this program with the ultimate goal of treating a wide range of patients infected with HCV."

The proof-of-concept trial in HCV-infected patients is a Phase I/II randomized, parallel-arm, double-blind, placebo-controlled study evaluating the safety and antiviral activity of IDX320 in treatment-naive adult patients infected with chronic hepatitis C. The study will evaluate four doses of IDX320, ranging from 50 to 400 mg once-per-day, administered for three days. Each cohort of the study will evaluate eight patients randomized six to IDX320 and two to placebo.  

About IDX320

IDX320, a macrocyclic HCV protease inhibitor, is an inhibitor of NS3/4A proteases from genotypes 1a, 1b, 2a and 4a (IC50 values from 0.8 to 1.9 nM), as well as from genotype 3a (IC50=23 nM). IDX320 did not inhibit nine tested cellular proteases (IC50 > 10 uM) in vitro, suggesting high selectivity. IDX320 bound tightly to the HCV protease enzyme with a long dissociation half-life (> 9 hours). After single 2 mg/kg oral doses of IDX320 in two animal species, favorable bioavailability and a long plasma half-life were observed, with substantial plasma concentrations 24 hours post dose. Comparable drug exposure was confirmed in healthy volunteers (n=6) receiving a single 200 mg oral dose. Further, no significant in vitro inhibition of human drug metabolizing enzymes, CYP450s and UGT1A1, by IDX320 suggests low potential for drug-drug interactions in patients.

About IDX184

IDX184 is a novel, liver-targeted nucleotide prodrug of 2'-methyl guanosine monophosphate, which includes Idenix's proprietary liver-targeting technology. This technology enables the delivery of nucleoside monophosphate to the liver, leading to the formation of high levels of nucleoside triphosphate, potentially maximizing drug efficacy and limiting systemic side effects with low, once-daily dosing. IDX184 in combination with pegylated interferon and ribavirin has demonstrated a generally favorable safety profile and potent antiviral activity in an ongoing Phase IIa study.

About HCV

Hepatitis C virus is a common blood-borne pathogen infecting three to four million people worldwide annually. Currently, an estimated 170 million people are infected worldwide, representing a nearly 5-fold greater prevalence than human immunodeficiency virus.(1)

About Idenix

Idenix Pharmaceuticals, Inc., headquartered in Cambridge, Massachusetts, is a biopharmaceutical company engaged in the discovery and development of drugs for the treatment of human viral diseases. Idenix's current focus is on the treatment of patients with chronic hepatitis C infection. For further information about Idenix, please refer to

Forward-looking Statements  

This press release contains "forward-looking statements" for purposes of the safe harbor provisions of The Private Securities Litigation Reform Act of 1995, including but not limited to the statements regarding the company's future business and financial performance. For this purpose, any statements contained herein that are not statements of historical fact may be deemed forward-looking statements. Without limiting the foregoing, the words "expect," "plans," "anticipates," "will," "expects," "goal," "estimates," "projects," "would," "could," "targets," and similar expressions are also intended to identify forward-looking statements, as are expressed or implied statements with respect to the company's clinical development programs or commercialization activities in hepatitis C, or any potential pipeline candidates, including any expressed or implied statements regarding the efficacy and safety of our drug candidates, the likelihood and success of any future clinical trials involving our drug candidates or successful development of novel combinations of direct-acting antivirals for the treatment of hepatitis C. Actual results may differ materially from those indicated by such forward-looking statements as a result of risks and uncertainties, including but not limited to the following: there can be no guarantees that the company will advance any clinical product candidate or other component of its potential pipeline to the clinic, to the regulatory process or to commercialization; management's expectations could be affected by unexpected regulatory actions or delays; uncertainties relating to, or unsuccessful results of, clinical trials, including additional data relating to the ongoing clinical trials evaluating its product candidates; the company's ability to obtain additional funding required to conduct its research, development and commercialization activities; the company's dependence on its collaborations with Novartis Pharma AG and GlaxoSmithKline; changes in the company's business plan or objectives; the ability of the company to attract and retain qualified personnel; competition in general; and the company's ability to obtain, maintain and enforce patent and other intellectual property protection for its product candidates and its discoveries. Such forward-looking statements involve known and unknown risks, uncertainties and other factors that may cause actual results to be materially different from any future results, performance or achievements expressed or implied by such statements. These and other risks which may impact management's expectations are described in greater detail under the heading "Risk Factors" in each of the company's annual report on Form 10-K for the year ended December 31, 2009 and quarterly report on form 10-Q for the quarter ended March 31, 2010, as filed with the Securities and Exchange Commission (SEC) and in any subsequent periodic or current report that the company files with the SEC.  All forward-looking statements reflect the company's estimates only as of the date of this release (unless another date is indicated) and should not be relied upon as reflecting the company's views, expectations or beliefs at any date subsequent to the date of this release. While Idenix may elect to update these forward-looking statements at some point in the future, it specifically disclaims any obligation to do so, even if the company's estimates change.

(1.)  Lavanchy (2009) Liver International. 29(s1):74-81.

Idenix Pharmaceuticals Contacts:

Teri Dahlman: 617-995-9905 (media)

Jonae Barnes: 617-224-4485 (investors)

SOURCE Idenix Pharmaceuticals, Inc.